The Withdrawal Agreement Bill now requires only Royal Assent from the Queen to become law, ratifying the Brexit deal reached with Brussels by the prime minister last October.
The European Parliament is expected to add its ratification on 29 January, allowing an orderly end to the UK’s 47-year membership of the continent-wide bloc on Friday next week.
Under the terms of Mr Johnson’s deal, the UK will pay around £30 billion to the EU in settlement of its liabilities, guarantee the rights of Europeans living in Britain, erect a customs border down the Irish Sea and lose all representation on the bloc’s decision-making bodies. But it will remain subject to EU rules during a transition period lasting until the end of 2020, while negotiations take place on a future partnership in areas like trade and security.
The completion of the Bill’s parliamentary stages came as peers opted not to challenge Mr Johnson’s defeat of four amendments to the legislation approved by the House of Lords earlier this week – including protections for the family reunion rights of unaccompanied child migrants after Brexit.
The defeat of the so-called Dubs Amendment – named after its author Lord Dubs, a wartime child refugee from the Nazis – was condemned by charities including Save the Children, who said it “puts some of the world’s most vulnerable and desperate children at even greater risk of harm”.
Mr Johnson’s bill completed its parliamentary stages after just 11 days of scrutiny in the two houses, securing a 99-vote majority at third reading in the Commons earlier this month.
Its smooth passage came after a tortuous year-long wrangle at Westminster as Theresa May’s version of the agreement was voted down three times, once by a historic record margin of 230 votes.
The stalemate eventually forced her resignation last July and was broken only by last month’s general election, in which Mr Johnson secured an 80-seat majority, assuring him of victory in future Commons divisions and dashing remaining hopes of a confirmatory Final Say referendum on his deal.